# DF-3447 -- VERDICT

**REPRODUCED** (impact=none, confidence=certain)
Guest: DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026  root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64

## Summary
Kernel mbuf-path BPF_LD|BPF_H|BPF_ABS ignores m_xhalf failure (merr unchecked, unlike the BPF_W twin two cases above): an out-of-range halfword load yields A=0 and the filter KEEPS RUNNING - fail-open. Live proof on vtnet0 (bpf_mtap mbuf path): the H filter accepted 5/5 pings while the identical W filter rejected 5/5.

## How it was verified
- Method: Live PoC on the QEMU guest (stock INVARIANTS kernel)
- Kernel references: sys/net/bpf_filter.c:238-247, sys/net/bpf.c:1325
- Evidence: live1.log DF-3447 section: packet 1-5 captured-by-H=1 captured-by-W=0
- Reachability: local-unpriv where noted in the summary; root-config for tun/lagg/carp/ipfw3/gre items; remote-facing for the packet parsers (wlan harnesses model the RX/TX path verbatim because the guest has no 802.11 hardware; precedent DF-0393/DF-0594/DF-0621/DF-0350).
- Privesc assessment: no uid0 chain exists for any finding in this batch -- the memory-safety items are bounded info reads (kernleak bucket) or fault-injection-gated NULL derefs; nothing yields a write primitive or control over privileged state. The one panic-class live item (DF-3414) is root-only (SIOCIFDESTROY).

## Fix
fix_status: not_testable -- Two-line fix (check merr, return 0 like the W path); kernel not rebuilt for this root-only filter-semantics Low item.
fix.diff: natural one-line/class fix authored against the read-only sys/ tree (never applied there).


## Fix status (batch validation)
Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest `make -j6 nativekernel KERNCONF=X86_64_GENERIC` completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.